U.S. patent application number 11/662139 was filed with the patent office on 2007-10-25 for viscosity modifier for lubricating oils, additive composition for lubricating oils, and lubricating oils compositions.
This patent application is currently assigned to MITSUI CHEMICALS, INC.. Invention is credited to Satoshi Ikeda, Royousuke Kaneshige, Akihiro Matsuda, Keiji Okada.
Application Number | 20070249508 11/662139 |
Document ID | / |
Family ID | 36036450 |
Filed Date | 2007-10-25 |
United States Patent
Application |
20070249508 |
Kind Code |
A1 |
Matsuda; Akihiro ; et
al. |
October 25, 2007 |
Viscosity Modifier for Lubricating Oils, Additive Composition for
Lubricating Oils, and Lubricating Oils Compositions
Abstract
A viscosity modifier for lubricating oils or an additive
composition for lubricating oils, which is excellent in
oil-thickening properties and can provide lubricating oil
compositions excellent in low-temperature characteristics and
handleability at low temperatures; and lubricating oil compositions
excellent in low-temperature characteristics and handleability at
low temperatures. The viscosity modifier comprises an
ethylene/.alpha.-olefin copolymer (B) which comprises (i) a
structural unit derived from ethylene, (ii) a structural unit
derived from an .alpha.-olefin having 3 to 19 carbon atoms, and
(iii) a structural unit derived from a higher .alpha.-olefin having
4 to 20 carbon atoms whose carbon number is by one or more larger
than that of the .alpha.-olefin having the unit (ii) which has the
following properties of (1) and (2): (1) the contents of units (i),
(ii) and (iii) are 25-49 mol %, 15-55 mol %, and 9-40 mol %
respectively (with the proviso that the total of the units (i),
(ii) , and (iii) is 100 mol %) and (2) the intrinsic viscosity
[.eta.] is 0.5 to 5.0 dl/g.
Inventors: |
Matsuda; Akihiro;
(Ichihara-shi, JP) ; Kaneshige; Royousuke;
(Kisarazu-shi, JP) ; Ikeda; Satoshi;
(Ichihara-shi, JP) ; Okada; Keiji; (Ichihara-shi,
JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
MITSUI CHEMICALS, INC.
5-2, HIGASHI-SHIMBASHI 1-CHOME
MINATO-KU, TOKYO
OH
105-7117
LUBRIZOL CORORATION, THE
29400, LAKELAND BOULEVARD
WICKLIFFE
44092-2298
|
Family ID: |
36036450 |
Appl. No.: |
11/662139 |
Filed: |
September 8, 2005 |
PCT Filed: |
September 8, 2005 |
PCT NO: |
PCT/JP05/16512 |
371 Date: |
March 8, 2007 |
Current U.S.
Class: |
508/591 |
Current CPC
Class: |
C10N 2020/04 20130101;
C10M 143/06 20130101; C08F 2420/02 20130101; C10M 2203/1006
20130101; C10M 2205/022 20130101; C10M 143/08 20130101; C08F
4/65912 20130101; C10N 2020/02 20130101; C08F 210/16 20130101; C10N
2030/02 20130101; C08F 4/65908 20130101; C08F 210/06 20130101; C08F
210/06 20130101; C08F 4/6592 20130101; C08F 210/16 20130101; C08F
4/6592 20130101; C08F 210/16 20130101; C08F 210/06 20130101; C08F
210/14 20130101; C08F 2500/17 20130101; C08F 2500/03 20130101; C08F
2500/20 20130101; C10M 2205/022 20130101; C10M 2205/026 20130101;
C10M 2205/022 20130101; C10M 2205/024 20130101; C10M 2205/026
20130101; C10M 2205/022 20130101; C10M 2205/024 20130101; C10M
2205/028 20130101; C10M 2205/022 20130101; C10M 2205/028
20130101 |
Class at
Publication: |
508/591 |
International
Class: |
C10M 143/06 20060101
C10M143/06 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 10, 2004 |
JP |
2004-263953 |
Claims
1. A viscosity modifier for lubricating oils comprising an
ethylene/.alpha.-olefin copolymer (B) which comprises: (i) a
structural unit derived from ethylene; (ii) a structural unit
derived from an .alpha.-olefin having 3 to 19 carbon atoms; and
(iii) a structural unit derived from a higher .alpha.-olefin having
4 to 20 carbon atoms whose carbon number is by one or more larger
than that of the structural unit derived from an .alpha.-olefin
having 3 to 19 carbon atoms, and has the following properties of
(1) and (2): (1) it contains 25 to 49 mol % of the structural unit
(i) derived from ethylene, 15 to 55 mol % of the structural unit
(ii) derived from an .alpha.-olefin having 3 to 19 carbon atoms,
and 9 to 40 mol % of the structural unit (iii) derived from a
higher .alpha.-olefin having 4 to 20 carbon atoms, wherein the
total molar amount of the structural units (i), (ii), and (iii) is
100 mol %; (2) the intrinsic viscosity ([.eta.]) is in the range of
0.5 to 5.0 dl/g as measured in decalin at 135.degree. C.
2. The viscosity modifier for lubricating oils according to claim
1, wherein the ethylene/.alpha.-olefin copolymer (B) has the
following property of (3): (3) Mw/Mn is 2.4 or less, where Mw is
weight average molecular weight and Mn is number average molecular
weight.
3. The viscosity modifier for lubricating oils according to claim 1
or 2, wherein the ethylene/.alpha.-olefin copolymer (B) has the
following property of (4): (4) the heat of fusion (.DELTA.H) as
measured by DSC is 5.0 J/g or less.
4. The viscosity modifier for lubricating oils according to any one
of claims 1 to 3, wherein the ethylene/.alpha.-olefin copolymer (B)
has the following property of (5): (5) the intensity ratio D is 0.5
or less, where D is the ratio of S.alpha..beta. to S.alpha..alpha.
(S.alpha..beta./S.alpha..alpha.) as measured by .sup.13C-NMR.
5. An additive composition for lubricating oils which comprises (A)
oil and (B) the ethylene/.alpha.-olefin copolymer according to any
one of claims 1 to 4, and contains said ethylene/.alpha.-olefin
copolymer (B) in a ratio of 1 to 30% by weight, wherein the total
amount of (A) and (B) is 100% by weight.
6. A lubricating oil composition comprises (AA) a lubricating oil
base, (B) the ethylene/.alpha.-olefin copolymer according to any
one of claims 1 to 4, and (C) a pour-point depressant and contains
said ethylene/.alpha.-olefin copolymer (B) in a ratio of 0.1 to 5%
by weight and the pour-point depressant (C) in a ratio of 0.05 to
5% by weight, wherein the weight of said lubricating oil
composition is 100% by weight.
Description
TECHNICAL FIELD
[0001] The present invention relates to a viscosity modifier for
lubricating oils, an additive composition for lubricating oils, and
lubricating oil compositions. More specifically, the present
invention relates to a viscosity modifier for lubricating oils or
an additive composition for lubricating oils which is excellent in
oil-thickening properties and can provide lubricating oil
compositions excellent in low-temperature properties and
handleability at low temperatures; and lubricating oil compositions
excellent in low-temperature characteristics and handleability at
low temperatures.
BACKGROUND ART
[0002] Petroleum products generally exhibit a large variation in
viscosity with variation in temperature. For lubricating oils used
for automobiles or the like, it is preferable that such a
temperature dependence of viscosity is small. In order to decrease
the temperature dependence of viscosity, an ethylene/.alpha.-olefin
copolymer having an effect of improving viscosity index is widely
used as an ingredient blended in lubricating oils.
[0003] Further, lubricating oils lose fluidity at low temperatures
because wax components therein solidify to crystals. In order to
lower the solidifying temperature, lubricating oils also contain a
pour-point depressant. The pour-point depressant prevents a
three-dimensional network structure from forming through
crystallization of wax components in lubricating oils, lowering the
pour point of the lubricating oils.
[0004] Among low-temperature characteristics of lubricating oils
which contain an ethylene/.alpha.-olefin copolymer and a pour-point
depressant, the viscosity at a high shear rate is determined by
compatibility between a lubricating oil base and the
ethylene/.alpha.-olefin copolymer, while the viscosity at a low
shear rate is strongly affected by the pour-point depressant. It is
known that when an ethylene/.alpha.-olefin copolymer having a
specific composition is used, the effect of a pour-point depressant
is remarkably lowered through interaction of the copolymer with the
pour-point depressant (refer to Patent document 1 and Patent
document 2).
[0005] For this reason, an ethylene/.alpha.-olefin copolymer
blended in lubricating oils, especially lubricating oils which are
requested to have excellent low-temperature properties, is required
not to impair the function of a pour-point depressant as well as to
possess excellent performance of improving viscosity index.
[0006] In order to avoid the interaction between a pour-point
depressant and an ethylene/.alpha.-olefin copolymer, it has been
proposed to use, as a viscosity index improver, an
ethylene/.alpha.-olefin copolymer having ununiform composition
distribution, which is obtained by using a specific polymerization
apparatus under specific polymerization conditions (refer to Patent
document 3). However, no lubricating oils excellent in
low-temperature characteristics at any shear rate were
obtained.
[0007] As a method for improving low-temperature characteristics of
lubricating oils, there is also mentioned a method where an
ethylene/propylene copolymer having a high ethylene content is
added as a viscosity index improver. In this method,
low-temperature characteristics were improved with increasing
ethylene content, but in some cases the ethylene sequence in the
viscosity index improver crystallized at low temperatures,
lubricating oil compositions themselves jellified, lowering
handleability.
[0008] Further, even in a case where a copolymer having a high
ethylene content was suitably used as a viscosity modifier for
lubricating oils, the composition sometimes jellified at low
temperatures when the molecular weight was over a given range or
the ethylene copolymer had a wider composition distribution even a
little or the like
[0009] Thus, property tolerance of the employed copolymer can not
be so wide, and the properties need to be strictly controlled.
[0010] In the above circumstances, the present inventors have
intensively investigated and found that a specific copolymer which
comprises a structural unit derived from ethylene, a structural
unit derived from an .alpha.-olefin having 3 to 19 carbon atoms,
and a structural unit derived from an .alpha.-olefin having 4 to 20
carbon atoms does not impair the function of a pour-point
depressant due to the above-mentioned interaction and that the
amount of copolymer blended can be reduced because a high molecular
weight copolymer can be prepared. That is, the copolymer works as a
viscosity modifier for lubricating oils which is excellent in
oil-thickening ability. Further, this copolymer has suitably
adjusted compatibility with a lubricating oil base at low
temperatures, providing lubricating oil compositions excellent in
low-temperature characteristics in entire range of shear rate and
excellent in handleability at low temperatures. Based on this
finding, the present invention has been accomplished. [0011] Patent
document 1: U.S. Pat. No. 3,697,429; [0012] Patent document 2: U.S.
Pat. No. 3,551,336; [0013] Patent document 3: Japanese Patent
Laid-Open Publication No. 228600/1985.
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0014] It is an object of the present invention to provide a
viscosity modifier for lubricating oils or an additive composition
for lubricating oils, which is excellent in oil-thickening ability
and can provide lubricating oil compositions excellent in
low-temperature characteristics and handleability at low
temperatures; and lubricating oil compositions excellent in
low-temperature characteristics and handleability at low
temperatures.
Means for Solving the Problems
[0015] A viscosity modifier for lubricating oils according to the
present invention comprises an ethylene/.alpha.-olefin copolymer
(B) which comprises [0016] (i) a structural unit derived from
ethylene; [0017] (ii) a structural unit derived from an
.alpha.-olefin having 3 to 19 carbon atoms; and [0018] (iii) a
structural unit derived from a higher .alpha.-olefin having 4 to 20
carbon atoms whose carbon number is by one or more larger than that
of the structural unit derived from an .alpha.-olefin having 3 to
19 carbon atoms, and has the following properties of (1) and (2):
[0019] (1) it contains 25 to 49 mol % of the structural unit (i)
derived from ethylene, 15 to 55mol % of the structural unit (ii)
derived from an .alpha.-olefin having 3 to 19 carbon atoms, and 9
to 40 mol % of the structural unit (iii) derived from a higher
.alpha.-olefin having 4 to 20 carbon atoms, wherein the total molar
amount of the structural units of (i), (ii), and (iii) is 100 mol
%; [0020] (2) the intrinsic viscosity ([.eta.]) is in the range of
0.5 to 5.0 dl/g as measured in decalin at 135.degree. C.
[0021] In the present invention, it is preferable that the
ethylene/.alpha.-olefin copolymer (B) has at least one of the
following properties of (3) to (5): [0022] (3) Mw/Mn (Mw: weight
average molecular weight, Mn: number average molecular weight) is
2.4 or less; [0023] (4) heat of fusion as measured by DSC is 5.0
J/g or less; [0024] (5) intensity ratio D is 0.5 or less, where D
is the ratio of S.alpha..beta. to S.alpha..alpha.
(S.alpha..beta./S.alpha..alpha.) as measured by .sup.13C-NMR.
[0025] An additive composition for lubricating oils according to
the present invention comprises [0026] (A) oil, and [0027] (B) the
above-mentioned ethylene/.alpha.-olefin copolymer, containing 1 to
30% by weight of the ethylene/.alpha.-olefin copolymer (B), wherein
the total weight of (A) and (B) is 100% by weight.
[0028] A lubricating oil composition according to the present
invention comprises [0029] (AA) a lubricating oil base, [0030] (B)
the above-mentioned ethylene/.alpha.-olefin copolymer, and [0031]
(C) a pour-point depressant, containing 0.1 to 5% by weight of the
ethylene/.alpha.-olefin copolymer (B) and 0.05 to 5% by weight of
the pour-point depressant (C), wherein the weight of the
lubricating oil composition is 100% by weight.
Effect of the Invention
[0032] A viscosity modifier for lubricating oils or an additive
composition for lubricating oils according to the present invention
is excellent in oil-thickening properties and can provide
lubricating oil compositions excellent in low-temperature
characteristics and handleability at low temperatures.
[0033] Lubricating oil compositions according to the present
invention are excellent in low-temperature characteristics, and
exhibit excellent handleability without jellifying themselves at
low temperatures.
BEST MODE FOR CARRYING OUT THE INVENTION
[0034] The viscosity modifier for lubricating oils and lubricating
oil compositions according to the present invention are
specifically described below.
[0035] [Viscosity Modifier for Lubricating Oils]
[0036] The viscosity modifier for lubricating oils according to the
present invention comprises an ethylene/.alpha.-olefin copolymer
(B) (hereinafter, may be simply called "copolymer (B)") which
comprises (i) a structural unit derived from ethylene (hereinafter,
may be called "structural unit (i)"), (ii) a structural unit
derived from an .alpha.-olefin having 3 to 19 carbon atoms
(hereinafter, may be called "structural unit (ii)"), and (iii) a
structural unit derived from a higher .alpha.-olefin having 4 to 20
carbon atoms whose carbon number is by one or more larger than that
of the above-mentioned structural unit derived from an
.alpha.-olefin having 3 to 19 carbon atoms (hereinafter, may be
called "structural unit (iii)"), wherein the copolymer (B) has
properties described below.
[0037] As the structural unit (ii), specifically, there may be
mentioned a structural unit derived from propylene, 1-butene,
1-pentene, 1-hexene, 3-methyl-1-butene, 3-methyl-1-pentene,
3-ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene,
4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene,
3-ethyl-1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene,
1-hexadecene, 1-octadecene, 1-eicocene or the like. Of these, the
structural unit (ii) is preferably a structural unit derived from
an .alpha.-olefin having 3 to 9 carbon atoms, more preferably a
structural unit derived from an .alpha.-olefin having 3 to 7 carbon
atoms, still more preferably a structural unit derived from
propylene. When the copolymer (B) containing structural unit (ii)
derived from propylene is blended with lubricating oils,
lubricating oil compositions particularly excellent in
low-temperature characteristics can be prepared over a wide range
of ethylene content.
[0038] As the structural unit (iii), there may be specifically
mentioned 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene,
3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene,
4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene,
4-ethyl-1-hexene, 3-ethyl-1-hexene, 1-octene, 1-decene, 1-dodecene,
1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicocene or the like.
Of these, a structural unit derived from an .alpha.-olefin having 4
to 10 carbon atoms is preferable in the present invention, a
structural unit derived from an .alpha.-olefin having 4 to 8 carbon
atoms is more preferable, and a structural unit derived from
1-butene, 1-hexene, or 1-octene is particularly preferable. With
any of these carbon atom numbers, lubricating oil compositions
excellent in low-temperature characteristics can be prepared over a
wide range of ethylene content.
[0039] Within a range where the objects of the present invention
are not impaired, another monomer, that is, a monomer other than
.alpha.-olefins having 2 to 20 carbon atoms, is optionally
copolymerized up to about 10 mol % with respect to 100 mol %, as
the total, of the structural units of (i), (ii), and (iii).
However, it is preferred that any polyene compound is not contained
as a copolymer component. When the copolymer (B) does not contain
polyene compound as a copolymer component, the copolymer (B) is
excellent in heat resistance, particularly it is hardly oxidized or
colored, and further particularly excellent in lubrication property
when it is blended with lubricating oils.
[0040] The copolymer (B) has the following properties of (1) and
(2):
[0041] (1) The copolymer (B) comprises 25 to 49 mol % of the
structural unit (i) (repeating unit derived from ethylene), 15 to
55 mol % of the structural unit (ii) (repeating unit derived from
an .alpha.-olefin having 3 to 19 carbon atoms), and 9 to 40 mol %
of the structural unit (iii) (repeating unit derived from a higher
.alpha.-olefin having 4 to 20 carbon atoms whose carbon number is
by one or more larger than that of the repeating unit derived from
an .alpha.-olefin having 3 to 19 carbon atoms), wherein the total
molar amount of the structural units (i), (ii), and (iii) is 100
mol %.
[0042] Structural Unit (i)
[0043] The copolymer (B) comprises the structural unit (i) in a
content of 25 to 49 mol %, preferably 29 to 49 mol %, more
preferably 35 to 49 mol %, still more preferably 40 to 49 mol %.
Within this range of the content of the structural unit (i),
lubricating oil compositions particularly excellent in
low-temperature characteristics, such as viscosity at low
temperatures, can be prepared when the copolymer (B) is blended
with lubricating oils.
[0044] Structural Unit (ii)
[0045] The copolymer (B) comprises the structural unit (ii) in a
content of 15 to 55 mol %, preferably 18 to 42 mol %, more
preferably 20% to 40 mol %. Within this range of the content of the
structural unit (ii), lubricating oil compositions particularly
excellent in low-temperature characteristics can be prepared when
the copolymer (B) is blended with lubricating oils.
[0046] Structural Unit (iii)
[0047] The copolymer (B) comprises the structural unit (iii) in a
content of 9 to 40 mol %, preferably 10 to 38 mol %, more
preferably 10 to 35 mol %.
[0048] When the copolymer (B) used in the present invention, which
comprises the structural unit (i), the structural unit (ii), and
the structural unit (iii), has the above-described compositions,
one can obtain lubricating oil compositions having satisfactory
low-temperature characteristics and excellent handleability at low
temperatures.
[0049] The lubricating oil composition using copolymer (B) provides
good low temperature characteristics. That is, the copolymer (B)
has a wider range of ethylene content than that of a binary
copolymer made from ethylene and an .alpha.-olefin having three or
more carbon atoms. This can be confirmed as follows: the
relationship between the content of the structural unit derived
from ethylene and the MR viscosity and the relationship between the
content of a structural unit derived from ethylene and storage
stability at low temperatures are graphically represented for the
copolymer (B) which can be used in the present invention; from
these graphs, the range (or content) of the structural unit derived
from ethylene in which acceptable MR viscosity and storage
stability at low temperatures can be attained is determined; and
this range (or content) is compared with the acceptable range of
the structural unit derived from ethylene obtained when the
copolymer (B) is replaced with a binary copolymer made from
ethylene and an .alpha.-olefin having three or more carbon
atoms.
[0050] The composition of the copolymer (B) can be determined by
.sup.13C-NMR in accordance with the method described in "Handbook
of Polymer Analysis" (edited by the Japan Society for Analytical
Chemistry, Polymer analysis study group, published by Kinokuniya
Company Ltd.).
[0051] (2) The intrinsic viscosity ([.eta.]) of the copolymer (B)
as measured in decalin at 135.degree. C. is in the range of 0.5 to
5.0 dl/g. When the intrinsic viscosity ([.eta.]) is within this
range, the oil-thickening properties are excellent, whereby the
amount of the copolymer (B) required for obtaining a specific
viscosity of lubricating oils is reduced. As a result, one can
obtain lubricating oil compositions which hardly jellify at low
temperatures and are excellent in shear stability. The
oil-thickening properties are evaluated as described in examples.
That is, when the amount of the copolymer to be added to
lubricating oil compositions for attaining a given predetermined
dynamic viscosity of the lubricating oil compositions at
100.degree. C. is smaller, the oil-thickening property is evaluated
to be better.
[0052] When the intrinsic viscosity ([.eta.]) is in the range of
0.5 to 4.0 dl/g, preferably 1.0 to 3.0 dl/g, more preferably 1.5 to
2.5 dl/g, the copolymer (B) can particularly improve the viscosity
index of lubricating oils.
[0053] The copolymer (B) preferably has at least one of the
following properties of (3) to (5).
[0054] (3) The copolymer (B) has an Mw/Mn (Mw: weight average
molecular weight, Mn: number average molecular weight) of
preferably 2.4 or less, more preferably 2.2 or less. The Mw/Mn is
an index representing molecular weight distribution. The molecular
weight distribution is preferred to be 2.4 or less, because
viscosity of the lubricating oil exhibits good shear stability.
[0055] The copolymer (B) having an Mw/Mn within the above range can
be produced by using a metallocene-based catalyst described
later.
[0056] (4) The copolymer (B) has a heat of fusion (AH) of
preferably 5.0 J/g or less as measured by a differential scanning
calorimeter (DSC), more preferably from 0 to 5.0 J/g, still more
preferably from 0 to 4.0 J/g, particularly preferably from 0 to 3.0
J/g. The heat of fusion is preferred to be within this range,
because jellification hardly occurs at low temperatures in this
case.
[0057] The heat of fusion was determined from the area of
endothermic peaks of an endothermic curve recorded with a
differential scanning calorimeter (DSC). That is, a sample was
packed in an aluminum pan, heated to 200.degree. C. at a rate of
10.degree. C./min, kept at 200.degree. C. for 5 min, cooled to
minus 150.degree. C. at a rate of 20.degree. C./min, and heated
again at a rate of 10.degree. C./min, and the endothermic curve in
the second run was used for determination.
[0058] The copolymer (B) having a heat of fusion (.DELTA.H) in the
above range can be produced using a metallocene-based catalyst
described later. The heat of fusion (.DELTA.H) can be changed
within the above range by changing the content of the structural
unit derived from ethylene or the contents of the structural units
derived from .alpha.-olefins.
[0059] The copolymer (B) used in the present invention is
preferably a copolymer obtained by copolymerizing, with a catalyst
containing a metallocene compound and an ionized ionic compound,
which is described later, (i) ethylene, (ii) an .alpha.-olefin
having 3 to 19 carbon atoms, and (iii) a higher .alpha.-olefin
having 4 to 20 carbon atoms whose carbon number is by one or more
larger than that of the .alpha.-olefin (ii) having 3 to 19 carbon
atoms, in view of low-temperature characteristics of lubricating
oil compositions.
[0060] (5) The copolymer (B) has an intensity ratio D of preferably
0.5 or less, more preferably 0.3 or less, wherein D is the
intensity ratio of S.alpha..beta. to S.alpha..alpha.
(S.alpha..beta./S.alpha..alpha.) as obtained from a .sup.13C-NMR
spectrum.
[0061] When the copolymer (B) having an intensity ratio D
(S.alpha..beta./S.alpha..alpha.) of 0.5 or less is contained,
fluidity of lubricating oils at low temperatures can be improved
and lubricating characteristics at high temperatures can be also
improved. Further, balancing between these two properties, that is,
between fluidity at low temperatures and lubricating
characteristics at high temperatures, is particularly
excellent.
[0062] The S.alpha..beta. and S.alpha..alpha. which are obtained
from a .sup.13C-NMR spectrum are the peak intensities corresponding
to CH.sub.2 groups in the structural units derived from ethylene
and an .alpha.-olefin having 3 to 20 carbon atoms respectively.
They are two types of CH.sub.2 groups in the positions represented
below. ##STR1##
[0063] (In the formulae, R independently represents a hydrogen atom
or an alkyl group having 1 to 6 carbon atoms.)
[0064] The measured .sup.13C-NMR spectrum is analyzed in accordance
with the method described by J. C. Randall (Review Macromolecular
Chemistry Physics, C29, 201(1989)), and the S.alpha..beta. and
S.alpha..alpha. are determined.
[0065] The intensity ratio D is calculated from the ratio of
integrated values (areas) for each of the peaks. The intensity
ratio D thus obtained is generally considered to be a criterion
representing the ratio at which 1,2-addition of an .alpha.-olefin
is followed by 2,1-addition or the ratio at which 2,1-addition of
an .alpha.-olefin is followed by 1,2-addition. Therefore, a larger
value of this intensity ratio D shows more irregular bonding
orientation of the .alpha.-olefin. To the contrary, a smaller value
of D shows more regular bonding orientation of the
.alpha.-olefin.
[0066] The copolymer (B) with such properties exhibits a large
effect of improving viscosity index when it is blended with a
lubricating oil base and does not impair the function of a
pour-point depressant.
[0067] The copolymer (B) having an intensity ratio D within the
above range can be produced by using a metallocene-based catalyst
described later. By modifying the molecular structure of the
metallocene-based catalyst, the intensity ratio D can be changed
within the range described above. The intensity ratio D can be also
changed by changing the polymerization temperature.
[0068] By using the copolymer (B) as a viscosity modifier, there
can be provided lubricating oils capable of satisfying the standard
for low-temperature characteristics specified by GF-4 standard,
which is the next-generation North American standard for
lubricating oils. Whether lubricating oils satisfy GF-4 standard or
not can be judged by measuring the CCS viscosity and the MR
viscosity as described later.
[0069] The copolymer (B) used as a viscosity modifier for
lubricating oils in the present invention can be obtained by
copolymerizing ethylene, an .alpha.-olefin having 3 to 19 carbon
atoms, a higher .alpha.-olefin having 4 to 20 carbon atoms whose
carbon number is by one or more larger than that the .alpha.-olefin
having 3 to 19 carbon atoms (hereinafter, simply called "higher
.alpha.-olefin having 4 to 20 carbon atoms") and, if necessary,
another monomer in the presence of an olefin polymerization
catalyst.
[0070] As such olefin polymerization catalyst, there may be used a
catalyst composed of a compound of transition metal such as
zirconium, hafnium, titanium and the like and an organoaluminum
compound (organoaluminum oxy-compound) and/or an ionized ionic
compound. Of these, a catalyst particularly suitably used in the
present invention is a metallocene-based catalyst which composed of
a metallocene compound of transition metal selected from Group 4 of
the Periodic Table or the like and an organoaluminum oxy-compound
and/or an ionized ionic compound.
[0071] In the following, the metallocene-based catalyst will be
described.
[0072] As a metallocene compound composed of transition metal
selected from Group 4 of the Periodic Table which forms the
metallocene-based catalyst, there may be mentioned a metallocene
compound described from line 5 at page 16 to line 4 at page 19 in
the pamphlet of WO01/85880, which is specifically represented by
the following general formula (a): ML.sub.x (a)
[0073] In formula (a), M is transition metal selected from Group 4
of the Periodic Table, specifically zirconium, titanium, or
hafnium;
[0074] x is valency of the transition metal; and
[0075] L is a ligand coordinating to the transition metal. At least
one of these ligands L is a ligand having a cyclopentadienyl
skeleton, and the ligand having a cyclopentadienyl skeleton
optionally has a substituent.
[0076] As the ligand having a cyclopentadienyl skeleton, there may
be mentioned, for example, a cyclopentadienyl group, an alkyl- or
cycloalkyl-substituted cyclopentadienyl group, an indenyl group, a
4,5,6,7-tetrahydroindenyl group, and a fluorenyl group. These
groups are optionally substituted with a halogen atom, a
trialkylsilyl group or the like.
[0077] When the compound represented by general formula (a) has two
or more groups having a cyclopentadienyl skeleton as ligand L,
among these groups, two groups having a cyclopentadienyl skeleton
may be bonded to each other through a (substituted) alkylene group,
a (substituted) silylene group or the like.
[0078] As a ligand L other than the ligand having a
cyclopentadienyl skeleton, there may be mentioned a hydrocarbon
group having 1 to 12 carbon atoms, an alkoxy group, an aryloxy
group, a sulfonic acid containing group (--SO.sub.3R.sup.a, wherein
R.sup.a is an alkyl group, a halogenated alkyl group, an aryl
group, or an aryl group substituted with a halogen atom or an alkyl
group), a halogen atom, a hydrogen atom and the like.
[0079] Examples of metallocene compounds which contain zirconium as
M and have at least two ligands having a cyclopentadienyl skeleton
are listed below:
[0080] bis(methylcyclopentadienyl)zirconium dichloride,
[0081] bis(ethylcyclopentadienyl)zirconium dichloride,
[0082] bis(n-propylcyclopentadienyl)zirconium dichloride,
[0083] bis(indenyl)zirconium dichloride,
[0084] bis(4,5,6,7-tetrahydroindenyl)zirconium dichloride and the
like.
[0085] Further, there may be also mentioned compounds wherein
zirconium metal in the above compounds is replaced with titanium
metal or hafnium metal.
[0086] In the present invention, as the metallocene compound, there
may be used a compound represented by the following general formula
(b): L.sup.1M.sup.1X.sub.2 (b)
[0087] (In the formula, M.sup.1 is a metal of Group 4 or of the
lanthanide series of the Periodic Table;
[0088] L.sup.1 is a derivative of a delocalized .pi.-bonding group,
providing the active metal site of M.sup.1 with a constraint
geometry; and
[0089] X each independently is a hydrogen atom, a halogen atom, or
a hydrocarbon, silyl, or germyl group containing 20 or less carbon,
silicon or germanium atoms.) Among the compounds represented by
general formula (b), a preferred compound is represented by the
following general formula (c): ##STR2##
[0090] In the formula, M.sup.1 is titanium, zirconium, or
hafnium;
[0091] X is the same as described above;
[0092] Cp is a substituted cyclopentadienyl group having a
substituent Z which bonds to M.sup.1 through .alpha.-bond;
[0093] Z is oxygen, sulfur, boron, or an element of Group 14 of the
Periodic Table (for example, silicon, germanium, or tin);
[0094] Y is a ligand containing nitrogen, phosphorus, oxygen, or
sulfur; and
[0095] Z and Y may form a condensed ring.
[0096] As the compound represented by general formula (c), there
may be mentioned, specifically, [0097]
[dimethyl(t-butylamido)(tetramethyl-.eta..sup.5-cyclopentadienyl)silane]t-
itanium dichloride, [0098]
[(t-butylamido)(tetramethyl-.eta..sup.5-cyclopentadienyl)-1,2-ethanediyl]-
titanium dichloride, [0099]
[dibenzyl(t-butylamido)(tetramethyl-.eta..sup.5-cyclopentadienyl)silane]t-
itanium dichloride, [0100]
[dimethyl(t-butylamido)(tetramethyl-.eta..sup.5-cyclopentadienyl)silane]d-
ibenzyltitanium, [0101]
[dimethyl(t-butylamido)(tetramethyl-.eta..sup.5-cyclopentadienyl)silane]d-
imethyltitanium, [0102]
[(t-butylamido)(tetramethyl-.eta..sup.5-cyclopentadienyl)-1,2-ethanediyl]-
dibenzyltitanium, [0103]
[(methylamido)(tetramethyl-.eta..sup.5-cyclopentadienyl)-1,2-ethanediyl]d-
ineopentyltitanium, [0104]
[(phenylphosphido)(tetramethyl-.eta..sup.5-cyclopentadienyl)
methylene]diphenyltitanium, [0105]
(dibenzyl(t-butylamido)(tetramethyl-.eta..sup.5-cyclopentadienyl)silane]d-
ibenzyltitanium, [0106]
[dimethyl(benzylamido)(.eta..sup.5-cyclopentadienyl)
silane]di(trimethylsilyl)titanium, [0107]
[dimethyl(phenylphosphido)(tetramethyl-.eta..sup.5-cyclopentadienyl)silan-
e]dibenzyltitanium, [0108]
[(tetramethyl-.eta..sup.5-cyclopentadienyl)-1,2-ethanediyl]dibenzyltitani-
um, [0109]
[2-.eta..sup.5-(tetramethylcyclopentadienyl)-1-methylethanolato(2-)]diben-
zyltitanium, [0110]
[2-.eta..sup.5-(tetramethylcyclopentadienyl)-1-methylethanolato(2-)]dimet-
hyltitanium, [0111]
[2-((4a,4b,8a,9,9a-.eta.)-9H-fluoren-9-yl)cyclohexanolato(2-)]dimethyltit-
anium, [0112]
[2-((4a,4b,8a,9,9a-.eta.)-9H-fluoren-9-yl)cyclohexanolato(2-)]dibenzyltit-
anium and the like.
[0113] Further, there may be also mentioned compounds wherein the
titanium metal in the above-described compounds is replaced with
zirconium metal or hafnium metal.
[0114] These metallocene compounds may be used solely or in
combination of two or more kinds thereof.
[0115] In the present invention, as the metallocene compound
represented by the general formula (a), a zirconocene compound
which contains zirconium as a central metal atom and at least two
ligands having a cyclopentadienyl skeleton is preferably used. The
metallocene compound represented by the general formula (b) or (c)
preferably contains titanium as the central metal atom. Among the
above-described metallocene compounds, a particularly preferred one
is a compound represented by general formula (c) containing
titanium as the central metal atom.
[0116] An organoaluminum oxy-compound which forms the
metallocene-based catalyst may be a publicly known aluminoxane as
described from line 24 at page 21 to line 6 from the bottom at page
22 in the pamphlet of WO01/85880. It may be an organoaluminum
oxy-compound which is insoluble in benzene.
[0117] As an ionized ionic compound which forms the
metallocene-based catalyst, there maybe mentioned a Lewis acid, an
ionic compound and the like.
[0118] As the Lewis acid, there may be mentioned a compound
represented by BR.sub.3, wherein R is a phenyl group optionally
substituted with a fluorine atom, a methyl group, a trifluoromethyl
group or the like; or a fluorine atom.
[0119] As the ionic compound, there may be mentioned trialkylated
ammonium salt, N,N-dialkylanilinium salt, dialkylammonium salt,
triarylphosphonium salt and the like.
[0120] These Lewis acids and ionic compounds are publicly known as
exemplified, for example, from line 1 to line 6 at page 23, and
from line 10 at page 23 to line 7 at page 24, respectively, in the
pamphlet of WO01/85880.
[0121] Further, as the ionic compound, there may be also mentioned
triphenylcarbenium tetrakis(pentafluorophenyl)borate,
N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate,
ferrocenium tetra(pentafluorophenyl)borate and the like. In
particular, an ionized ionic compound is suitably used, for
regulating the composition distribution of the
ethylene/.alpha.-olefin copolymer (B).
[0122] For forming the metallocene-based catalyst, an
organoaluminum compound may be used in combination with an
organoaluminum oxy-compound and /or an ionized ionic compound. As
the organoaluminum compound, there may be mentioned a compound
represented by the following general formula (f):
R.sup.1.sub.nAlX.sub.3-n (f)
[0123] In the formula, R.sup.1 represents a hydrocarbon group
having 1 to 15 carbon atoms, preferably 1 to 4 carbon atoms; X
represents a halogen atom or a hydrogen atom; and n is a number of
1 to 3.
[0124] Such organoaluminum compound is publicly known as
exemplified, for example, from line 23 at page 24 to line 5 at page
26 in the pamphlet of WO01/85880.
[0125] In the presence of the above-mentioned metallocene-based
catalyst, ethylene, an .alpha.-olefin having 3 to 19 carbon atoms,
a higher .alpha.-olefin having 4 to 20 carbon atoms, and, if
necessary, another monomer are copolymerized generally in a liquid
phase. As a polymerization solvent, a hydrocarbon solvent is
generally used but an .alpha.-olefin such as propylene may be
used.
[0126] As the hydrocarbon solvent used in polymerization, there may
be used aliphatic hydrocarbons such as pentane, hexane, heptane,
octane, decane, dodecane, and kerosene and halogenated derivatives
thereof; alicyclic hydrocarbons such as cyclohexane,
methylcyclopentane, and methylcyclohexane and halogenated
derivatives thereof; and aromatic hydrocarbons such as benzene,
toluene and xylene, and halogenated derivatives thereof such as
chlorobenzene. These solvents may be used solely or in combination
of two or more kinds thereof.
[0127] Ethylene, an .alpha.-olefin having 3 to 19 carbon atoms, a
higher .alpha.-olefin having 4 to 20 carbon atoms, and, if
necessary, another monomer may be copolymerized either by batch
method or by continuous process, but continuous copolymerization is
preferred. Continuous copolymerization using a stirred tank reactor
is particularly preferred. In continuous copolymerization, the
metallocene-based catalyst is used, for example, at the following
concentration.
[0128] The concentration of metallocene compound in a
polymerization system is generally 0.00005 to 0.1 mmol/L
(polymerization volume), preferably 0.0001 to 0.05 mmol/L. The
organoaluminum oxy-compound is supplied in such an amount that the
molar ratio of aluminum atom to transition metal of the metallocene
compound in the polymerization system (Al/transition metal) becomes
1 to 10000, preferably 10 to 5000.
[0129] The ionized ionic compound is supplied in such an amount
that the molar ratio of the ionized ionic compound to the
metallocene compound in the polymerization system (ionized ionic
compound/metallocene compound) becomes 0.5 to 30, preferably 1 to
25.
[0130] When an organoaluminum compound is used, the concentration
thereof is generally about 0 to 5 mmol/L (polymerization volume),
preferably about 0 to 2 mmol/L.
[0131] In the case of copolymerizing ethylene, an .alpha.-olefin
having 3 to 19 carbon atoms, a higher .alpha.-olefin having 4 to 8
carbon atoms, and, if necessary, another monomer in the presence of
the above-mentioned metallocene-based catalyst, copolymerization is
carried out under conditions wherein the temperature is generally
from minus 20.degree. C. to 150.degree. C., preferably from
0.degree. C. to 120.degree. C., more preferably from 0.degree. C.
to 100.degree. C., and the pressure is over 0 and 80 kg/cm.sup.2 or
below, preferably over 0 and 50 kg/cm.sup.2 or below. The
above-mentioned polymerization conditions are preferably kept
constant in continuous polymerization.
[0132] The reaction time (average retention time in the case of
continuous copolymerization), which depends on conditions such as
catalyst concentration, and polymerization temperature, is
generally 5 min to 5 hr, preferably 10 min to 3 hr.
[0133] Ethylene, an .alpha.-olefin having 3 to 19 carbon atoms, a
higher .alpha.-olefin having 4 to 20 carbon atoms, and, if
necessary, another monomer are supplied to the polymerization
system in such amounts that the copolymer (B) having the
above-described specific composition can be obtained. In addition,
a molecular weight modifier such as hydrogen may be used in
copolymerization.
[0134] When ethylene, an .alpha.-olefin having 3 to 19 carbon
atoms, a higher .alpha.-olefin having 4 to 20 carbon atoms, and, if
necessary, another monomer are copolymerized as described above,
the copolymer (B) is obtained as a polymerization solution
containing the copolymer. The polymerization solution is treated in
a usual manner, providing the copolymer (B) used in the present
invention.
[0135] [Additive Composition for Lubricating Oils]
[0136] An additive composition for lubricating oils according to
the present invention is a composition which contains oil (A) and
the copolymer (B).
[0137] At first, each component composing the additive composition
for lubricating oils according to the present invention is
explained.
[0138] <(A) Oil>
[0139] Oil (A) used in the present invention includes mineral oils
and synthetic oils such as poly-.alpha.-olefin, polyol ester,
diesters such as dioctyl phthalate and dioctyl sebacate, and
polyalkylene glycol. Mineral oils or blends of mineral oils and
synthetic oils are preferably used. Mineral oils subjected to a
purification step such as dewaxing or the like are generally used,
and have several grades designated in accordance with purification
procedures. Generally a mineral oil having a wax content of 0.5 to
10% is used. One may also use a highly purified oil which is
produced, for example, by hydrocracking purification and has a low
pour point, a high viscosity index, and a composition mainly
composed of isopraffin. Generally, the oil having a kinematic
viscosity at 40.degree. C. of 10 to 200 cSt is used.
[0140] As described above, mineral oils are used generally after a
purification step such as dewaxing and are classified into several
grades which are defined by API (American Petroleum Institute)
classification. The properties of lubricating oil bases which are
classified into each of the groups are shown in Table 1.
TABLE-US-00001 TABLE 1 Saturated hydrocarbon Sulfur Viscosity
content *2 content *3 Group Kind index *1 (% by volume) (% by
weight) (i) *4 mineral oil 80 to 120 <90 >0.03 (ii) mineral
oil 80 to 120 .gtoreq.90 .ltoreq.0.03 (iii) mineral oil .gtoreq.120
.gtoreq.90 .ltoreq.0.03 (iv) poly-.alpha.-olefin (v) lubricating
oil base other than the above *1: Measured in accordance with ASTM
D445 (JIS K2283) *2: Measured in accordance with ASTM D3238 *3:
Measured in accordance with ASTM D4294 (JIS K2541) *4: Group (i)
includes mineral oils having a saturated hydrocarbon content of
less than 90% by volume and a sulfur content of less than 0.03% by
weight; mineral oils having a saturated hydrocarbon content of not
less than 90% by volume and a sulfur content of more than 0.03% by
volume; and mineral # oils having a saturated hydrocarbon content
of less than 90% by volume and a sulfur content of more than 0.03%
by weight.
[0141] Poly-.alpha.-olefin in Table 1 is a hydrocarbon polymer
which is obtained by polymerizing at least an .alpha.-olefin having
10 or more carbon atoms as a raw material monomer, and polydecene
obtained by polymerizing 1-decene is exemplified.
[0142] The oil (A) used in the present invention is preferably the
oil belonging to any of groups (i) to (iv). Particularly preferable
oil is a mineral oil having a kinematic viscosity at 100.degree. C.
of 1 to 50 mm.sup.2/s and a viscosity index of 80 or more, or
poly-.alpha.-olefin. Further, mineral oils belonging to group (ii)
or group (iii) or poly-.alpha.-olefin belonging to group (iv) are
preferred as the oil (A). Oils belonging to group (ii) or group
(iii) tend to have a lower wax content as compared with oils
belonging to group (i). Particularly, the most preferable oil is a
mineral oil which belongs to group (ii) or group (iii) and has a
kinematic viscosity at 100.degree. C. of 1 to 50 mm.sup.2/s and a
viscosity index of 80 or more, or poly-.alpha.-olefin belonging to
group (iv).
[0143] <(B) Copolymer>
[0144] As copolymer (B) used in the present invention, the
above-described copolymer (B) which is a viscosity modifier for
lubricating oils is used.
[0145] That is, there is used the copolymer (B) which comprises (i)
a structural unit derived from ethylene, (ii) a structural unit
derived from an .alpha.-olefin having 3 to 19 carbon atoms, and
(iii) a structural unit derived from a higher .alpha.-olefin having
4 to 20 carbon atoms whose carbon number is by one or more larger
than that of the structural unit derived from an .alpha.-olefin
having 3 to 19 carbon atoms, and has the following properties of
(1) and (2): [0146] (1) it contains 25 to 49 mol % of the
structural unit (i), 15 to 55 mol % of the structural unit (ii),
and 9 to 40 mol % of the structural unit (iii) (the total molar
amount is 100 mol %) [0147] (2) the intrinsic viscosity ([.eta.])
is 0.5 to 5.0 as measured in decalin at 135.degree. C.
[0148] The structural unit (ii) composing the copolymer (B) is
preferably propylene. The structural unit (iii) composing the
copolymer (B) is preferably 1-butene, 1-hexene, or 1-octene.
[0149] A copolymer that is particularly preferred as the copolymer
(B) comprising 29 to 49 mol % of the structural unit (i), 20 to 40
mol % of the structural unit (ii), and 10 to 35 mol % of the
structural unit (iii), as described above.
[0150] It is preferred that the copolymer (B) has at least one of
the following properties of (3) to (5): [0151] (3) Mw/Mn is 2.4 or
less; [0152] (4) heat of fusion (.DELTA.H) as measured by DSC is
5.0 J/g or less; [0153] (5) intensity ratio D is 0.5 or less, where
D is the ratio of S.alpha..beta. to S.alpha..alpha.
(S.alpha..beta./S.alpha..alpha.) as measured by .sup.13C-NMR.
[0154] An additive composition for lubricating oils according to
the present invention comprises the copolymer (B) and oil (A). The
content of (B) is from 1 to 30% by weight and that of oil (A) is
from 99% by weight to 70% by weight, wherein the total amount of
(A) and (B) is 100% by weight. Preferably the content of (B) is
from 1 to 20% by weight and that of oil (A) is from 99% by weight
to 80% by weight. More preferably the content of (B) is from 5 to
10% by weight and that of oil (A) is from 95% by weight to 90% by
weight. In the present invention, in addition to the components (A)
and (B), other components such as a thermal stabilizer may be
contained in a small amount within the range where the objects of
the present invention are not impaired.
[0155] The additive composition for lubricating oils according to
the present invention is a composition which contains the component
(A) in the above-described amount, so that, for example, by mixing
this composition with other components for lubricating oil
compositions in producing the lubricating oil compositions, a
specific viscosity suitable for lubricating oils can be attained
with a reduced amount of the component (B) added. That is, this
composition is excellent in oil-thickening property. Further, by
using said additive composition for lubricating oils, lubricating
oil compositions excellent in low-temperature characteristics and
handleability at low temperatures can be obtained. Since the
additive composition for lubricating oils according to the present
invention is a composition containing the oil (A), as described
above, it has good workability at the time of addition and can be
readily mixed with the other components.
[0156] [Lubricating Oil Compositions]
[0157] Lubricating oil compositions according to the present
invention are compositions which comprise a lubricating oil base
(AA), the above-mentioned copolymer (B), and a pour-point
depressant (C).
[0158] At first, each component composing the lubricating oil
compositions according to the present invention is explained.
[0159] <(AA) Lubricating Oil Base>
[0160] The lubricating oil base (AA) used in the present invention
includes mineral oils and synthetic oils such as
poly-.alpha.-olefin, polyol ester, diesters such as dioctyl
phthalate and dioctyl sebacate, and polyalkylene glycol. Mineral
oils or blends of mineral oils and synthetic oils are preferably
used. Mineral oils subjected to a purification step such as
dewaxing or the like are generally used, and have several grades
designated in accordance with purification procedures. Generally
mineral oils having a wax content of 0.5 to 10% are used. One may
also use a highly purified oil which is produced, for example, by
hydrocracking purification and has a low pour point, a high
viscosity index, and a composition mainly composed of isopraffin.
The oils having a kinematic viscosity at 40.degree. C. of 10 to 200
cSt are generally used.
[0161] Mineral oils are generally used after a purification step
such as dewaxing or the like as described above, and are classified
into several grades which are defined by API (American Petroleum
Institute) classification. The properties of lubricating oil bases
classified into each of the groups were shown in above-described
Table 1.
[0162] Poly-.alpha.-olefin in Table 1 is a hydrocarbon polymer
obtained by polymerizing at least an .alpha.-olefin having 10 or
more carbon atoms as a raw material monomer, as exemplified by
polydecene obtained by polymerizing 1-decene.
[0163] The lubricating oil base (AA) used in the present invention
is preferably the oil which belongs to any of groups (i) to (iv).
Particularly, a mineral oil having a kinematic viscosity at
100.degree. C. of 1 to 50 mm.sup.2/s and a viscosity index of 80 or
more, or poly-.alpha.-olefin is preferred. Further, as the
lubricating oil base (AA), a mineral oil which belongs to group
(ii) or group (iii), or poly-.alpha.-olefin which belongs to group
(iv) is preferred. Oils of group (ii) and oils of group (iii) tend
to have lower wax content as compared with oils of group (i).
Particularly, the most preferable one is a mineral oil which
belongs to group (ii) or group (iii) and has a kinematic viscosity
at 100.degree. C. of 1 to 50 mm.sup.2/s and a viscosity index of 80
or more, or poly-.alpha.-olefin which belongs to group (iv).
[0164] <(B) Copolymer>
[0165] As the copolymer (B) used in the lubricating oil composition
of the present invention, the copolymer (B) which is the
above-described viscosity modifier for lubricating oils is
used.
[0166] <(C) Pour-Point Depressant>
[0167] The pour-point depressant used in the lubricating oil
composition of the present invention includes an alkylated
naphthalene, a (co)polymer of alkyl methacrylate, a (co)polymer of
alkyl acrylate, a copolymer of alkyl fumarate and vinyl acetate, an
.alpha.-olefin polymer, a copolymer of an .alpha.-olefin and
styrene, and the like. Of these, a (co)polymer of alkyl
methacrylate and a (co)polymer of alkyl acrylate are preferably
used.
[0168] The lubrication oil compositions according to the present
invention comprise the pour-point depressant (C) as well as the
lubricating oil base (AA) and the copolymer (B) which are described
above. In this lubricating oil compositions, the copolymer (B) is
contained in an amount of 0.1 to 5% by weight, preferably 0.2 to
1.5% by weight, more preferably 0.25 to 1.5% by weight,
particularly preferably 0.30 to 1.5% by weight; the pour-point
depressant (C) is contained in an amount of 0.05 to 5% by weight,
preferably 0.1 to 3% by weight, more preferably 0.1 to 2% by
weight, most preferably 0.2 to 1.5% by weight; and the remainders
are lubricating oil base (AA) and blending components which are
described later. Here, there are no particular limitations on the
amounts of the blending components other than (B) and (C), but the
upper limit of the ratio of (AA)/(blending components other than
(B) and (C)) is 100/0, preferably 99/1, more preferably 97/3, still
more preferably 95/5, wherein the total amount of lubricating oil
base (AA) and the blending components other than (B) and (C) is
100% by weight. The lower limit of the ratio of (AA)/(blending
components other than (B) and (C)), although it is not particularly
limited, is preferably 60/40, more preferably 70/30, particularly
preferably 85/15. The specific numerical range is, for example,
100/0 to 60/40, preferably 99/1 to 70/30, more preferably 97/3 to
80/20, still more preferably 95/5 to 85/15.
[0169] In the lubricating oil compositions of the present
invention, the effect of increasing viscosity can be obtained when
the content of the copolymer (B) is 0.1% by weight or more. When
the copolymer (B) has composition distribution, a component which
impairs the effect of the pour-point depressant (C) may be
contained. However, when the content of the copolymer (B) is 5% by
weight or less, the effect of the pour-point depressant (C) is not
impaired, and thus such a content of the copolymer (B) is
favorable. Therefore, when the content of the copolymer (B) is
within the above-described range, the excellent effect of
increasing viscosity is exerted, and lubricating oil compositions
having good fluidity at low temperatures can be obtained.
[0170] For such lubricating oil compositions, the temperature
dependence of viscosity is small, and elevation of pour point
caused by the interaction between the copolymer (B) and the
pour-point depressant (C) is reduced. These lubricating oil
compositions are excellent in low-temperature characteristics in
entire range of shear rate, handleability at low temperatures, and
lubricating performance.
[0171] The lubricating oil compositions according to the present
invention may contain, besides the lubricating oil base (AA), the
copolymer (B), and the pour-point depressant (C), blending
components having an effect of improving viscosity index such as a
(co)polymer of alkyl methacrylate, hydrogenated SBR, and SEBS, or
blending components such as detergents, rust preventives,
dispersants, extreme-pressure additives, antifoaming agents,
antioxidants, and metal deactivators.
[0172] The lubricating oil compositions according to the present
invention can be prepared, using publicly known conventional
methods, by mixing or dissolving the copolymer (B), the pour-point
depressant (C), and, if necessary, the other blending components in
the lubricating oil base (AA).
EXAMPLES
[0173] The present invention will be further described in detail
with reference to the following examples, but it should be
construed that the present invention is in no way limited to those
examples.
[0174] In the examples, the physical properties are measured as
described below.
[0175] <<Compositions of Copolymers>>
[0176] The composition was determined, using a nuclear magnetic
resonance spectrometer LA500 manufactured by JEOL Ltd., in a mixed
solvent of ortho-dichlorobenzene and benzene-d.sub.6
(ortho-dichlorobenzene/benzene-d.sub.6=3/1 to 4/1 (volume ratio))
at 120.degree. C. in a pulse width of 45.degree. for a pulse
repetition time of 5.5 seconds.
[0177] <<Mw/Mn>>
[0178] The Mw/Mn was measured using GPC (gel permeation
chromatography) in an ortho-dichlorobenzene solvent at 140.degree.
C.
[0179] <<Intrinsic Viscosity>>
[0180] The intrinsic viscosity was measured indecalin at
135.degree. C.
[0181] <<Heat of Fusion>>
[0182] The heat of fusion was obtained from the area of endothermic
peak of an endothermic curve which was measured by a differential
scanning calorimeter (DSC) ; that is, a sample was packed in an
aluminum pan, heated to 200.degree. C. at a rate of 10.degree.
C./min, kept at 200.degree. C. for 5 min, cooled to minus
150.degree. C. at a rate of 20.degree. C./min, and heated again at
a rate of 10.degree. C./min, and the endothermic curve recorded at
the second run was used for determination.
[0183] <<Viscosity at 100.degree. C. (K.V.)>>
[0184] The kinematic viscosity was measured based on ASTM D 445. In
the present examples, the K.V. (kinematic viscosity) of each sample
was regulated to be about 10 mm.sup.2/sec.
[0185] <<Cold Cranking Simulator (CCS) Viscosity>>
[0186] The CCS viscosity was measured based on ASTM D 2602. The CCS
viscosity was used for evaluation of sliding properties (starting
properties) at low temperatures at a crank shaft. When the value of
the CCS viscosity is smaller, the low-temperature characteristics
of lubricating oil are better.
[0187] <<Mini-Rotary Viscometer (MR) Viscosity>>
[0188] The MR viscosity was measured based on ASTM D 4684. The MR
viscosity was used for evaluation of pumping by an oil pump at low
temperatures. When the value of the MR viscosity is smaller, the
low-temperature characteristics of lubricating oil are better.
Polymerization Example 1
[0189] [Synthesis of Olefin Copolymers]
[0190] To a 1 L volume pressurized continuous polymerization
reactor equipped with a stirring blade and thoroughly purged with
nitrogen, 1 L of purified and dehydrated decane was introduced.
Decane was fed continuously at a rate of 600 mL/h, and the pressure
was increased so that the total pressure reached 3.8 MPa. After
that, a decane solution of triisobutylaluminum (0.2 mmol/L) was fed
continuously at a rate of 300 mL/h, and then a decane solution of
triphenylcarbenium (tetrakispentafluorophenyl)borate (0.006 mmol/L)
was fed continuously at a rate of 200 mL/h. Further, as a catalyst,
a 0.0015 mmol/L decane solution of
[dimethyl(t-butylamido)(tetramethyl-.eta..sup.5-cyclopentadienyl)silane]t-
itanium dichloride was fed continuously at a rate of 100 mL/h in
such a manner that no vapor phase existed in the polymerization
reactor. Meanwhile, from the top of the polymerization reactor, the
polymerization solution was drawn out so that the volume of the
polymerization solution in the polymerization reactor was
constantly 1 L. Then, ethylene at a rate of 27 NL/h, propylene a
rate of 0.4 L/h, octene a rate of 0.42 L/h, and hydrogen a rate of
0.3 NL/h were continuously fed to the polymerization reactor.
Copolymerization was conducted at 80.degree. C. by circulating
coolant and steam through jackets equipped outside of the
polymerization reactor.
[0191] By performing copolymerization under the above-described
conditions, a polymerization solution containing an
ethylene/propylene/octene copolymer was obtained. The resultant
polymerization solution was poured into a large amount of methanol
so as to deposit the ethylene/propylene/octane copolymer, which was
then dried under reduced pressure at 130.degree. C. for 24 hr. The
properties of the resulting polymer are shown in Table 2.
Polymerization Example 2
[0192] Copolymerization was conducted in a similar manner to
Polymerization Example 1 except that the flow rate of propylene was
changed to 0.23 L/h, that the flow rate of octene was changed to
0.78 L/h, and that the flow rate of hydrogen was changed to 1.0
NL/h. The properties of the resulting polymer are shown in Table
2.
Polymerization Example 3
[0193] Copolymerization was conducted in a similar manner to
Polymerization Example 1 except that the flow rate of propylene was
changed to 0.35 L/h and that 1-butene was fed in place of octene at
a flow rate of 0.4 L/h. The properties of the resulting polymer are
shown in Table 2.
Polymerization Example 4
[0194] Copolymerization was conducted in a similar manner to
Polymerization Example 1 except that the flow rate of propylene was
changed to 0.38 L/h and that 1-hexene was fed in place of octene at
a flow rate of 0.4 L/h. The properties of the resulting polymer are
shown in Table 2.
[Polymerization Example 5
[0195] To a 2 L volume stainless steel autoclave equipped with a
stirring blade and thoroughly purged with nitrogen, 900 mL of
heptane was introduced at 23.degree. C. To this autoclave, 50 NL of
propylene was introduced with rotating the stirring blade and
ice-cooling. Then, the autoclave was heated to 60.degree. C. and
pressurized with ethylene so that the total pressure became 0.8
MPa. When the inner pressure of the autoclave reached 0.8 MPa, 1.0
mL of a 1.0 mmol/mL hexane solution of triisobutylaluminum was fed
by nitrogen pressure. After that, 3 mL of a toluene solution
containing 0.2 mmol (in terms of Al) of methylaluminoxane, 0.002
mmol of bis(1,3-dimethylcyclopentadienyl)zirconium dichloride,
which was pre-prepared, was fed into the autoclave by nitrogen
pressure to start polymerization. Then, the inside temperature of
the autoclave was regulated at 60.degree. C. for 60 min, and
ethylene was directly fed so that pressure became 0.8 MPa. After 60
min from the start of polymerization, 5 ml of methanol was pumped
to the autoclave to terminate polymerization, and then the
autoclave was depressurized to atmospheric pressure.
[0196] The resulting polymerization solution was poured into a
large amount of methanol so as to deposit an ethylene/propylene
copolymer, which was then dried under reduced pressure at
130.degree. C. for 24 hr. The properties of the resulting polymer
are shown in Table 2. TABLE-US-00002 TABLE 2 Polymerization
Polymerization Polymerization Polymerization Polymerization Example
1 Example 2 Example 3 Example 4 Example 5 Polymer properties
Ethylene content (mol %) 46.1 46.2 48.1 46.8 47.8 Propylene content
(mol %) 39.5 22.2 38.4 38.9 52.2 Octene content (mol %) 14.4 31.6
-- -- -- Butene content (mol %) -- -- 13.5 -- -- Hexene content
(mol %) -- -- -- 14.3 -- [.eta.] (dl/g) 1.68 1.58 1.76 1.59 1.56
S.alpha..beta./S.alpha..alpha. (%) 0.16 0.16 0.16 0.16 0.16 Mw/Mn
1.9 2.0 1.8 2.0 2.1 Heat of fusion (J/g) 2.4 2.6 3.1 2.8 3.1
Polymerization Example 6
[0197] [Synthesis of Olefin Copolymers]
[0198] To a 1 L volume pressurized continuous polymerization
reactor equipped with a stirring blade and thoroughly purged with
nitrogen, 1 L of purified and dehydrated decane was introduced.
Decane was fed continuously at a rate of 600 mL/h, and the pressure
was increased so that the total pressure reached 3.8 MPa. After
that, a decane solution of triisobutylaluminum (TIBA) (0.2 mmol/L)
was fed continuously at a rate of 300 mL/h, then a decane solution
of triphenylcarbenium(tetrakispentafluorophenyl)borate (0.006
mmol/L) was fed continuously at a rate of 200 mL/h. Further, as a
catalyst, a 0.0015 mmol/L decane solution of
[dimethyl(t-butylamido)(tetramethyl-.eta..sup.5-cyclopentadienyl)silane]t-
itanium dichloride was fed continuously at a rate of 100 mL/h so
that no vapor phase existed in the polymerization reactor.
Meanwhile, from the top of the polymerization reactor, the
resulting polymerization solution was continuously drawn out so
that the volume of the polymerization solution in the
polymerization reactor was constantly 1 L. Then, ethylene at a rate
of 27 NL/h, propylene at a rate of 0.6 L/h, octene at a rate of
0.42 L/h, and hydrogen at a rate of 0.3 NL/h were continuously fed
to the polymerization reactor. Copolymerization was conducted at
80.degree. C. by circulating coolant and steam through jackets
equipped outside of the polymerization reactor.
[0199] By performing copolymerization under the above conditions, a
polymerization solution containing an ethylene/propylene/octane
copolymer was obtained. The resulting polymerization solution was
poured into a large amount of methanol to deposit the
ethylene/propylene/octene copolymer, which was then dried under
reduced pressure at 130.degree. C. for 24 hr. The properties of the
resulting polymer are shown in Table 3.
Polymerization Example 7
[0200] Copolymerization was conducted in a similar manner to
Polymerization Example 1 except that the flow rate of propylene was
changed to 0.21 L/h. The properties of the resulting polymer are
shown in Table 3. TABLE-US-00003 TABLE 3 Polymerization
Polymerization Polymer properties Example 6 Example 7 Ethylene
content (mol %) 35.6 60.2 Propylene content (mol %) 64.0 25.5
Octene content (mol %) 14.8 14.3 Butene content (mol %) -- --
Hexene content (mol %) -- -- [.eta.] (dl/g) 1.56 1.78
S.alpha..beta./S.alpha..alpha. (%) 0.16 0.16 Mw/Mn 2.0 1.9 Heat of
fusion (J/g) 1.2 8.2
Example 1
[0201] Using 87.18% by weight of a mineral oil "120 Neutral" (Trade
name, manufactured by ESSO Co., Ltd.), which was classified in the
group (ii) in Table 1, having a kinematic viscosity at 100.degree.
C. of 4.60 mm.sup.2/s, as a lubricating oil base, 0.82% by weight
of a polymer prepared in Polymerization Example 1 as a viscosity
index improver, 0.6% by weight of "ACLUBE 146" (Trade name,
manufactured by Sanyo Chemical Industries Ltd.) as a pour-point
depressant, and 11.4% by weight of "LZ20003C" (Trade name,
manufactured by The Lubrizol Corporation) as a
detergent-dispersant, a lubricating oil composition was prepared
and its properties were evaluated.
[0202] The results are shown in Table 4.
Examples 2 to 4 and Comparative Example 1
[0203] The procedure of Example 1 was repeated except that the
polymers each prepared in Polymerization Examples 2 to 5 were used
respectively as a viscosity index improver to evaluate the
lubricating oil composition as shown in Table 4. The results are
shown in Table 4. TABLE-US-00004 TABLE 4 Comparative Example 1
Example 2 Example 3 Example 4 Example 1 Polymer blended
Polymerization Polymerization Polymerization Polymerization
Polymerization Example 1 Example 2 Example 3 Example 4 Example 5
Composition (% by weight) Lubricating oil base 87.18 87.28 87.31
87.22 88.77 Detergent-dispersant 11.4 11.4 11.4 11.4 10.0
Pour-point depressant 0.6 0.6 0.6 0.6 0.5 Polymer 0.82 0.72 0.69
0.77 0.73 Properties of lubricating oil Kinematic viscosity at
10.94 10.89 11.02 10.98 10.24 100.degree. C. (mm.sup.2/s) CCS
viscosity at -30.degree. C. 5904 5764 5922 5822 6140 (mPa s) MR
viscosity at -35.degree. C. 28274 27765 29811 28910 40000 (mPa
s)
[0204] As is clearly shown in Table 4, the composition in which a
specific copolymer of ethylene, propylene and a higher
.alpha.-olefin having 4 to 20 carbon atoms is used as a viscosity
modifier for lubricating oils is better in low-temperature
characteristics such as CCS viscosity and MR viscosity as compared
with the composition in which a copolymer of ethylene and propylene
is used as a viscosity modifier for lubricating oils.
[0205] For lubricating oil compositions, low-temperature
characteristics such as CCS viscosity and MR viscosity are desired
to be improved as much as possible. For example, by increasing the
degree of purification of lubricating oil base, CCS viscosity can
be lowered, for example, by around 10 in the above measurement
value, or MR viscosity can be lowered, for example, by around 100
in the above measurement value (that is, the low-temperature
properties are improved), but it takes cost.
[0206] As opposed to the above case, according to the present
invention, the CCS viscosity and MR viscosity can be improved
without using any expensive methods. This is of great
significance.
Comparative Examples 2 and 3
[0207] The procedure of Example 1 was repeated except that the
polymers each prepared in Polymerization Examples 6 and 7 were used
respectively as a viscosity index improver to evaluate the
lubricating oil composition as shown in Table 5. The results are
shown in Table 5. TABLE-US-00005 TABLE 5 Comparative Comparative
Example 2 Example 3 Polymerization Polymerization Polymer blended
Example 6 Example 7 Composition (% by weight) Lubricating oil base
87.12 87.31 Detergent-dispersant 11.4 11.4 Pour-point depressant
0.6 0.6 Polymer 0.88 0.69 Properties of lubricating oils Kinematic
viscosity at 10.94 10.89 100.degree. C. (mm.sup.2/s) CCS viscosity
at -30.degree. C. 6410 5654 (mPa s) MR viscosity at -35.degree. C.
29931 48869 (mPa s)
* * * * *